4 files changed, 107 insertions, 19 deletions

diff --git a/drivers/ata/libata-sff.c b/drivers/ata/libata-sff.c
index 3c2d2289f85e..90d20c615ef5 100644
--- a/drivers/ata/libata-sff.c
+++ b/drivers/ata/libata-sff.c
@@ -247,7 +247,7 @@ u8 ata_sff_check_status(struct ata_port *ap)
  *      LOCKING:
  *      Inherited from caller.
  */
-u8 ata_sff_altstatus(struct ata_port *ap)
+static u8 ata_sff_altstatus(struct ata_port *ap)
 {
         if (ap->ops->sff_check_altstatus)
                 return ap->ops->sff_check_altstatus(ap);
@@ -256,6 +256,93 @@ u8 ata_sff_altstatus(struct ata_port *ap)
 }
 
 /**
+ *      ata_sff_irq_status - Check if the device is busy
+ *      @ap: port where the device is
+ *
+ *      Determine if the port is currently busy. Uses altstatus
+ *      if available in order to avoid clearing shared IRQ status
+ *      when finding an IRQ source. Non ctl capable devices don't
+ *      share interrupt lines fortunately for us.
+ *
+ *      LOCKING:
+ *      Inherited from caller.
+ */
+static u8 ata_sff_irq_status(struct ata_port *ap)
+{
+        u8 status;
+
+        if (ap->ops->sff_check_altstatus || ap->ioaddr.altstatus_addr) {
+                status = ata_sff_altstatus(ap);
+                /* Not us: We are busy */
+                if (status & ATA_BUSY)
+                        return status;
+        }
+        /* Clear INTRQ latch */
+        status = ata_sff_check_status(ap);
+        return status;
+}
+
+/**
+ *      ata_sff_sync - Flush writes
+ *      @ap: Port to wait for.
+ *
+ *      CAUTION:
+ *      If we have an mmio device with no ctl and no altstatus
+ *      method this will fail. No such devices are known to exist.
+ *
+ *      LOCKING:
+ *      Inherited from caller.
+ */
+
+static void ata_sff_sync(struct ata_port *ap)
+{
+        if (ap->ops->sff_check_altstatus)
+                ap->ops->sff_check_altstatus(ap);
+        else if (ap->ioaddr.altstatus_addr)
+                ioread8(ap->ioaddr.altstatus_addr);
+}
+
+/**
+ *      ata_sff_pause           -       Flush writes and wait 400nS
+ *      @ap: Port to pause for.
+ *
+ *      CAUTION:
+ *      If we have an mmio device with no ctl and no altstatus
+ *      method this will fail. No such devices are known to exist.
+ *
+ *      LOCKING:
+ *      Inherited from caller.
+ */
+
+void ata_sff_pause(struct ata_port *ap)
+{
+        ata_sff_sync(ap);
+        ndelay(400);
+}
+
+/**
+ *      ata_sff_dma_pause       -       Pause before commencing DMA
+ *      @ap: Port to pause for.
+ *
+ *      Perform I/O fencing and ensure sufficient cycle delays occur
+ *      for the HDMA1:0 transition
+ */
+ 
+void ata_sff_dma_pause(struct ata_port *ap)
+{
+        if (ap->ops->sff_check_altstatus || ap->ioaddr.altstatus_addr) {
+                /* An altstatus read will cause the needed delay without
+                   messing up the IRQ status */
+                ata_sff_altstatus(ap);
+                return;
+        }
+        /* There are no DMA controllers without ctl. BUG here to ensure
+           we never violate the HDMA1:0 transition timing and risk
+           corruption. */
+        BUG();
+}
+
+/**
  *      ata_sff_busy_sleep - sleep until BSY clears, or timeout
  *      @ap: port containing status register to be polled
  *      @tmout_pat: impatience timeout
@@ -742,7 +829,7 @@ static void ata_pio_sectors(struct ata_queued_cmd *qc)
         } else
                 ata_pio_sector(qc);
 
-        ata_sff_altstatus(qc->ap); /* flush */
+        ata_sff_sync(qc->ap); /* flush */
 }
 
 /**
@@ -763,8 +850,9 @@ static void atapi_send_cdb(struct ata_port *ap, struct ata_queued_cmd *qc)
         WARN_ON(qc->dev->cdb_len < 12);
 
         ap->ops->sff_data_xfer(qc->dev, qc->cdb, qc->dev->cdb_len, 1);
-        ata_sff_altstatus(ap); /* flush */
-
+        ata_sff_sync(ap);
+        /* FIXME: If the CDB is for DMA do we need to do the transition delay
+           or is bmdma_start guaranteed to do it ? */
         switch (qc->tf.protocol) {
         case ATAPI_PROT_PIO:
                 ap->hsm_task_state = HSM_ST;
@@ -905,7 +993,7 @@ static void atapi_pio_bytes(struct ata_queued_cmd *qc)
 
         if (unlikely(__atapi_pio_bytes(qc, bytes)))
                 goto err_out;
-        ata_sff_altstatus(ap); /* flush */
+        ata_sff_sync(ap); /* flush */
 
         return;
 
@@ -1489,14 +1577,10 @@ inline unsigned int ata_sff_host_intr(struct ata_port *ap,
                 goto idle_irq;
         }
 
-        /* check altstatus */
-        status = ata_sff_altstatus(ap);
-        if (status & ATA_BUSY)
-                goto idle_irq;
 
-        /* check main status, clearing INTRQ */
-        status = ap->ops->sff_check_status(ap);
-        if (unlikely(status & ATA_BUSY))
+        /* check main status, clearing INTRQ if needed */
+        status = ata_sff_irq_status(ap);
+        if (status & ATA_BUSY)
                 goto idle_irq;
 
         /* ack bmdma irq events */
@@ -2030,7 +2114,7 @@ void ata_sff_error_handler(struct ata_port *ap)
                 ap->ops->bmdma_stop(qc);
         }
 
-        ata_sff_altstatus(ap);
+        ata_sff_sync(ap);               /* FIXME: We don't need this */
         ap->ops->sff_check_status(ap);
         ap->ops->sff_irq_clear(ap);
 
@@ -2203,7 +2287,7 @@ void ata_bmdma_stop(struct ata_queued_cmd *qc)
                  mmio + ATA_DMA_CMD);
 
         /* one-PIO-cycle guaranteed wait, per spec, for HDMA1:0 transition */
-        ata_sff_altstatus(ap);        /* dummy read */
+        ata_sff_dma_pause(ap);
 }
 
 /**
@@ -2722,7 +2806,8 @@ EXPORT_SYMBOL_GPL(ata_sff_qc_prep);
 EXPORT_SYMBOL_GPL(ata_sff_dumb_qc_prep);
 EXPORT_SYMBOL_GPL(ata_sff_dev_select);
 EXPORT_SYMBOL_GPL(ata_sff_check_status);
-EXPORT_SYMBOL_GPL(ata_sff_altstatus);
+EXPORT_SYMBOL_GPL(ata_sff_dma_pause);
+EXPORT_SYMBOL_GPL(ata_sff_pause);
 EXPORT_SYMBOL_GPL(ata_sff_busy_sleep);
 EXPORT_SYMBOL_GPL(ata_sff_wait_ready);
 EXPORT_SYMBOL_GPL(ata_sff_tf_load);
diff --git a/drivers/ata/pata_icside.c b/drivers/ata/pata_icside.c
index 17138436423d..cf9e9848f8b5 100644
--- a/drivers/ata/pata_icside.c
+++ b/drivers/ata/pata_icside.c
@@ -270,7 +270,7 @@ static void pata_icside_bmdma_stop(struct ata_queued_cmd *qc)
         disable_dma(state->dma);
 
         /* see ata_bmdma_stop */
-        ata_sff_altstatus(ap);
+        ata_sff_dma_pause(ap);
 }
 
 static u8 pata_icside_bmdma_status(struct ata_port *ap)
diff --git a/drivers/ata/pata_rb532_cf.c b/drivers/ata/pata_rb532_cf.c
index a108d259f19d..f8b3ffc8ae9e 100644
--- a/drivers/ata/pata_rb532_cf.c
+++ b/drivers/ata/pata_rb532_cf.c
@@ -57,7 +57,9 @@ static inline void rb532_pata_finish_io(struct ata_port *ap)
         struct ata_host *ah = ap->host;
         struct rb532_cf_info *info = ah->private_data;
 
-        ata_sff_altstatus(ap);
+        /* FIXME: Keep previous delay. If this is merely a fence then
+           ata_sff_sync might be sufficient. */
+        ata_sff_dma_pause(ap);
         ndelay(RB500_CF_IO_DELAY);
 
         set_irq_type(info->irq, IRQ_TYPE_LEVEL_HIGH);
diff --git a/drivers/ata/pata_scc.c b/drivers/ata/pata_scc.c
index e965b251ca24..bbf5aa345e68 100644
--- a/drivers/ata/pata_scc.c
+++ b/drivers/ata/pata_scc.c
@@ -726,7 +726,7 @@ static void scc_bmdma_stop (struct ata_queued_cmd *qc)
                  in_be32(bmid_base + SCC_DMA_CMD) & ~ATA_DMA_START);
 
         /* one-PIO-cycle guaranteed wait, per spec, for HDMA1:0 transition */
-        ata_sff_altstatus(ap);  /* dummy read */
+        ata_sff_dma_pause(ap);  /* dummy read */
 }
 
 /**
@@ -747,7 +747,8 @@ static u8 scc_bmdma_status (struct ata_port *ap)
                 return host_stat;
 
         /* errata A252,A308 workaround: Step4 */
-        if ((ata_sff_altstatus(ap) & ATA_ERR) && (int_status & INTSTS_INTRQ))
+        if ((scc_check_altstatus(ap) & ATA_ERR)
+                                        && (int_status & INTSTS_INTRQ))
                 return (host_stat | ATA_DMA_INTR);
 
         /* errata A308 workaround Step5 */